Falkirk-based Alexander Dennis Ltd (ADL) has signed a framework deal with the Republic of Ireland’s National Transport Authority (NTA) for the delivery of up to 600 Enviro400ER double-deck hybrid buses, capable of running in zero-emission mode for at least 2.5km; the agreement includes an initial firm order for 100 buses.

The ‘single supplier’ framework agreement covers the purchase of double-deck diesel-electric hybrid buses and will run for up to five years.

ADL (www.alexander-dennis.com) was selected through a comprehensive procurement process, in which the company provided the most economically advantageous offer.

The first 100 buses are due to be delivered in the autumn, and the NTA will be able to exercise options for another 500 vehicles over the coming years.

The Enviro400ER uses the BAE Systems Series-ER hybrid system with a 32kWh next-generation lithium-ion battery energy storage system that can be charged via a plug-in connection, meeting the requirements of the European Union’s Clean Vehicles Directive.

In addition to its continuous ‘zero tailpipe emissions’ range, the Enviro400ER switches off its diesel engine at low speeds during the approach to and departure from stops (and when stationary).

Each of the first 100 buses will seat 66 passengers, with separate spaces for wheelchair users and for passengers travelling with buggies.

The framework agreement provides the opportunity to adjust the specifications of later vehicles to suit other operating requirements.

Alexander Dennis chief executive Colin Robertson said: “This order confirms our strategy of leading the market with the widest range of low- and zero-emission buses, enabling us to offer the right vehicle for each requirement.”